Im prove m ent in ph otolithog raph y



UNITED .STATES J. vW. t)seolamvjr',r 0F MELBOURNE,'.AUsTRMnA, assienoe'ro SAMUEL THOMPSON HOQBER, AOF,A oHaarEs'ro'*Wut-vnussaotiUsE'rfrs.` 1

IM PajovE MV lan-r` mf PH o'roLlTi-l oeRAP'l-l Y;

Speeitlcationforniing 'part of Letters Patent NdjG-Grdated une 25,`1861.

. To all whom it 'may concer-n',-

V Beitknownthan,JOHNWLTEROSBORN, ofthe'cityoflilelbourne,inthecountyotfourke, in the Colony of Victoria, in the Doniinons of Her Britannie Majesty, have invented a new and Improved Mode of Preparing-Photolithographic. Transfers;andJlZdo hereby declare that the following is .a full'andexact descrip- .tion thereof. 'd i v e Thenatureofmyinvention consistsintheuse ofa. coatin g of album'en upon paper+-suhjected, as hereinafter described, to coagnlationas a basis-` for the'production of photolithographic tran sfers,fand in the use of gelatine in intimate v'connection with the, said albumen for the formationof'a surface of organic matter'upon the paper 'of a nature fitted toA receive the vjphotv graphic picture, and. at the saine time'to he` have toward the lithographieretranster-ink in a manner calculated to produce 4the bestde- '.scriptiou of photolithographic transfers;

To 'enable others' -'skilled ini-,the art of photolithography to make use of' my invention, I v will proceed to describehow'the processmuy beperforined.' y u llake a sheet of plain positive photographic paper, dampen it and when-ithas beomequite flat cover it -with the tbllowiugfsolutiouz v`wa-vv 4 ter, eight ounces; albumeu; twoounees; gela tine, eight hundred grains, jandbichrom'ate of potash vfour hundred and fortygrains; d The gelatine, wit h the finely-powdei ed biehroinatm may be soaked in the" whole quantityv'of waiter for three or four hours'in the' dark,- and may then bemelted by input-arisingr 'theliask containing it in hot water, takingcare not to raise'the heat higher than necessary. fWhen the temperature ofthe melted contents of thev tiask hasfallen' to about 1100 Fahrenheitthe albumen may be added, and very 1well finixed;

andthe whole' allowed togreposefor a time. 'lhe albulnen for this pnrpose'should have been.

`whipped to 'a froth andthe requiredquantity measured ott' after subsidence. I t should also be obtained from fresh ems. Toxapply thisy 'solntionlto thesurface of the paper, theiullowiugor anymore `convenient method may be adopted:v g

Lay the paper, face down, ou a btmrdfnear4 one end of which is ad justcd a trough coutaini ing'the mixture before mentioned cooled to thev which piece of wood-stehld he so adjusted as just to press the under surface of the paper into the bichrolnate mixture' as the paper is drawn-under"the'rontnlrd edge ofthe saine upward from thetrough.

The bichromate solution or inixturehereinbefore-described may he varied as to quanti? ties,-or by thesuhst'itution or addition otrother t ingredient ts--sluch as gum, su gar,'chr0m ic acid ,orlanyf other ehroinate or biehromate or any ot' the salts fof uranium or other chemicals of .similar propertiesso 'far as such can be used without impair-ing the'advantages arising from 4a. preponderanceof aloumen' orinterfering with the characteristic 'property possessed by gelatine otf swelling in cold water.

facture of whiclrliasbeen described; may also with equally goed results be prepared by coatf i ing 'tl1e"plaiu. paper with two solutions, the first to'consistof one part albumenLwith from one to two parts water,. which,.at`ter the paper hasdried, is `to be followed hyanother consistin'gofwater, eightonnoes.; gelatine, six h'un-4 dred and fortyy grains; bichromate of potash, th'ree'hundred and titty-.two grains. In whichever way' the photolithographic transfer-paper [is made, it should be dried in a perfectly dar-k and warlnfrooin and 'then' passed through a lithographie press upon" a copper plate in'` orf der -to glaze and atten it. A negative of -the .object to he photoli'thographed is now tojbc taken and the sheet ot'paper prepared as above -to beexposed u'nderit in aphotographic pressure-frame usedfor making positives in sunlight-fromone half'minut-efto six minutes, or: more, -f necessary. ,This photographic-posh tive print is next to be inked in byA passing it' through a. lithographie press with its face to ward a lithographie stone 'or plate, said stone or plate having been first evenl5r rolled inwith lithographieretrausierink,` When the paper is pulled oi' the stone the. greasy iukshon'ld Abe found to be of sucha. thickness, -as to' dis-v closethe positive print dimly through it.

y -The photographic trauslrpaper, the manuy f 'The next operation*isl'fau-iiuportsnt.part-'of .my invention. `Its object is `to effect tbe'c'cagulation `of the-albumen .combined with the Sensitive coating. i With this in' v iew'tlxc inked Aprintl should now' be placed in-.a'darkened room, swimming on -boiliu g water? contained in a. tray or disil,'the-'inhed sidegu'pwnrd,excluding airbubbleswhere it should 'be left-until vtlie'weter is cold.' A distinctive feature ot" .my process is avnilingin'yself of the sivellingfproporties of. gelatine', .which 'changeis brought about lin` the sensitive 'coating vsimultaneously with .that otcoagulationwhile thepap'er is 'swimmingupon tiie'iwnter.k The e'eot of these swelling 'propertiesof'uualtered gelatine is' to i cause the alteredportions of the-gelatine which don'ot swell to become'.reiatirelyjdepressed, 1 wberebythe inkopen said depressed parts'is protected during.' the washing-,off process,

which'i done as follows: The priu't isJohe placedece upward, upon n smooth board' and washedotl' gently' with a clean soft sponge dippediuf water.' Whentheprint is clean enough pinjil; Afast to the' lmnrdnnd pour a large quantity. ofboiling' water orerit from s kettleorother vessel. New lay' the print, face up,en the boilingwater and 'let itilont until.

theguppersurta is'dry, which soontakes place it' the* water isl 1ot, nnd'the p'rint'left surrounded'w'ith an in'ky border. When time albuminisedsurface isdrylitt the; pnperfoli the water, ley it onv blotting-paper, and then -tinish dryingin any couvcnient'manuer. This -transfer'msy now' be transferred 'to a litho;A

grephicston'ein the-ordinary way, or Ato ,the surface cf a zinc'plate for zincographi'c printing, or toa copper plate to be used as ,a .guide for engravingoncopper,`or-to any.-surface ot' wood, metal, stone, paper.. or cloth, glass, india-rubber, leatherrguttc-perche,v or com posi-v Ition..."

' My process orinethoddiers material-ly. from v that described in Newtons patent. By 'New-l tonsprocessthephotographicpictureis thrown -upona lithographie `stone or zinc plate prepared for the purposcby direct Vexposure fun'- adheres 'eventually to thosepart-s ot' saidpre .pared surface where the light Vhas notncted, whereas I do not' .work u'pon the stone or zinc direct, but upon-a. prepared surface vupon pa-y per, whereby n positive transfer is made upon which theiuk will hefound adherent to those sensitized coating is applied.. `-I'e usesV plain.

peper, or paper' sited with' starch, 'while nmy process the existence of 'a 4 costing of a'slbnnien.V n i'nder the workprerents the' greasy inkfrom spreading into' the ber or -pcres'ct 'the paper, which wouldinj'urethe clearness'otf the lines.`

Asser lso washes and wets,V hisfex'posed transfer-before inking it.- Colonel 'Jamess methodV practiced in the British Ordiuillce 4Survey 0 lice,A also ditiersf'from mine, inasmuch tts-he usesgnm'in preparing his photographicltrans. Afer-paper, `wlnvenens I use a. compound iilm o't -.albumen and gelstine,each ofthese-snbstances .plnyng'an important' part. The albumen -in my lprocess,while it is easily applied to' the paper in its uncoagnlatedstat'e, resists, after 'that'change has been, elected'init bythe acv tion o't the boiling water, every attempt to wash ,it away.' f j The work, therefore,- is found eventnally-to beupon albnmenized peper, which, be- ;sides improving its quality, 'plays a very impot 4tant part by constituting an underlyingadliesive coating which adheres rmly to thelithof graphic stone or other' substance during the operationof' tt'a 11sl'e x"1ing. inY the lithographie press,'in consequence whereof the paper cannot-slip, which'wonld-cause' the work to,be

come thickened or doubled.' -The compoundl nim of albumen' and gelatine up'on which work ennblesmealso to erivegreatadvantages ,from the manner in which i those parts/of ,it

-unactedup'on fby light s we'il up when floating' the inked print upon the boiling water, this change in' the exposed `and'nked surfacecaus- '-ing' the work to beeom e considerably depressed,

whereby' the ink upon itis' protected' from the rubbing acti'on'ot 'thesponge and. the' maximum amount'of firmness and 'clearness is the' iresult;.' 1nthis respect myprocess di'ers mn.- terially froi'n 'Colonel Jamess-.andall others.` From the foregoing references'it will be seen that I do not cluimt'o'be the original inventor' of photclithography. l

. Viihatfl cleinx as'uiyinven'tion,` anddesi-re to secure-by Letters Patent, is-

v 1. The pre'pnratiou and ns'e, in making pho?-v olithographic transfers, of a paper prepared byapplying,in conjuuctionwith the-sensitizing. substances, or' preceding 'their .-applica tions, a'.; coating of albumen to the surface of -the paper und co'ngulntiug the'albu'ineu'so ap plied'by'heat -in the .manner and'for alle pur? poses hereinbelore described,

2. "Ibe'use'and Aapplication of gelatine, in `conjunction with albumen, for the -formatiou ot' theconting oforgani'c'matter applied to the surface ofphotoli-thographic transfer paper,l whichgelatine, by'it's swelling properties, when acted upon by moisture, as -I'have'explained, enables me to 4obtain the results -hereinhetore described;

Witnesses: y

.J oHN VAN DARLINGTON,

HUGH McGRAW.' 

